1. Field of the Invention
The present application claims the Paris Convention priority based on Japanese Patent Application No. 2009-226690 filed on Sep. 30, 2009, the entire content of which is incorporated herein by reference.
The present invention relates to a process for producing a complex oxide catalyst, using a complex oxide containing molybdenum and cobalt as a raw material.
2. Description of the Related Art
Complex oxide catalysts containing molybdenum and cobalt hitherto have been widely used. Examples of such complex oxide catalysts include a complex oxide catalyst for use in production of acrolein and acrylic acid by vapor phase catalytic oxidization of propylene with a molecular oxygen (Patent Publications 1 and 2); a complex oxide catalyst for use in production of acrylic acid by vapor phase catalytic oxidization of propane with a molecular oxygen (Patent Publication 3); a complex oxide catalyst for use in production of acrylonitrile by vapor phase catalytic ammoxidation of propylene or propane with a molecular oxygen and ammonia (Patent Publications 3 to 5); a complex oxide catalyst for use in production of methacrolein and methacrylic acid by vapor phase catalytic oxidization of isobutylene or tertiary butyl alcohol with a molecular oxygen (Patent Publication 1); a complex oxide catalyst for use in production of methacrylonitrile by vapor phase catalytic ammoxidation of isobutylene or tertiary butyl alcohol with a molecular oxygen and ammonia (Patent Publications 4 and 5); and a complex oxide catalyst for use in production of acrylic acid by vapor phase catalytic oxidization of acrolein with a molecular oxygen (Patent Publication 6).
In general, any of these complex oxide catalysts is obtained by mixing raw materials for catalyst with water to form an aqueous solution or aqueous slurry, drying the resulting aqueous solution or aqueous slurry, and calcining the resultant dried solid. As the raw materials for such a catalyst, compounds each containing one of the respective elements which constitute the catalyst are used in required amounts. That is, there are used, as the raw materials, a molybdenum-containing compound, a cobalt-containing compound, and optionally, a compound which contains a catalyst-constituting element other than molybdenum and cobalt (cf. Patent Publications 1 to 6).
Patent Publication 1: JP-A-2008-231044
Patent Publication 2: JP-A-2005-187460
Patent Publication 3: JP-A-2002-239382
Patent Publication 4: JP-A-2006-061888
Patent Publication 5: JP-A-7-51570
Patent Publication 6: JP-A-7-10802
However, the complex oxide catalysts obtained by the conventional processes are not always sufficient in their catalytic activities in the vapor phase catalytic oxidation reactions, especially in production of unsaturated aldehyde and unsaturated carboxylic acid.
An object of the present invention is therefore to provide a process for producing a complex oxide catalyst which exhibits a superior catalytic activity in vapor phase catalytic oxidation reaction, especially in production of unsaturated aldehyde and unsaturated carboxylic acid.